This invention pertains to electronic engine control. Some embodiments concern controlling the cylinder to cylinder variations of emissions of particulate matter and of oxides of nitrogen in exhaust gas of turbodiesel engines with exhaust gas recirculation. Other embodiments concern other engines, such as gasoline engines. Control is based on a periodic model instead of (or in addition to) being based on a cycle-averaged model.
Reducing cylinder to cylinder variations will reduce the average output of particulate matter and of oxides of nitrogen, and also will enable achieving a better trade-off between conflicting requirements for fuel economy and for emissions of particulate matter and of oxides of nitrogen.